This invention relates to training cartridges, most particularly to training cartridges which recycle the host firearm by telescopic expansion of the cartridge.
Telescopically expanding training cartridges are known, one example is described in the applicant's own U.S. Pat. No. 6,564,719 B2. A typical cartridge of the type described in that patent comprises a posterior portion which has a moveable member which is slidable rearwardly towards a breech block of a host firearm. The anterior portion has a gas passage there through and an expansion chamber is provided between the moveable member and the anterior portion. Gas generating means for providing gas within the cartridge are initiatable on firing of the firearm to propel the moveable member in a rearward direction so as to recycle the firearm. A second gas generating means is positioned forward of the gas passage and may be initiated by any suitable reaction caused on initiation of the posterior primer. For example, the shock or pressure wave generated on activation of the primer may be sufficient to initiate the second gas generating means, or alternatively, activation of the posterior primer may activate a secondary mechanical or electrical device which serves to initiate the second gas generating means.
In the above described prior art cartridges hot, high pressure gas from the posterior primer enters all of the major telescopically moving parts of the cartridge. This limits the choice of materials from which any thin section part of the cartridge assembly can be manufactured to metals which have sufficient resistance to these temperatures and pressures. Consequently, the anterior and posterior portions of the telescopically expanding recycling mechanism are made almost entirely of metals.